SummaryObesity associated disorders such as T2D, hypertension and CVD, commonly referred to as the “metabolic syndrome”, are prevalent diseases of industrialized societies. Deranged adipose tissue proliferation and differentiation contribute significantly to the development of these metabolic disorders. Comparatively little however is known, about how these processes influence the development of metabolic disorders. Using a multidisciplinary approach, I plan to elucidate molecular mechanisms underlying the altered adipocyte differentiation and maturation in different models of obesity associated metabolic disorders. Special emphasis will be given to the analysis of gene expression, postranslational modifications and lipid molecular species composition. To achieve this goal, I am establishing several novel methods to isolate pure primary preadipocytes including a new animal model that will allow me to monitor preadipocytes, in vivo and track their cellular fate in the context of a complete organism. These systems will allow, for the first time to study preadipocyte biology, in an in vivo setting. By monitoring preadipocyte differentiation in vivo, I will also be able to answer the key questions regarding the development of preadipocytes and examine signals that induce or inhibit their differentiation. Using transplantation techniques, I will elucidate the genetic and environmental contributions to the progression of obesity and its associated metabolic disorders. Furthermore, these studies will integrate a lipidomics approach to systematically analyze lipid molecular species composition in different models of metabolic disorders. My studies will provide new insights into the mechanisms and dynamics underlying adipocyte differentiation and maturation, and relate them to metabolic disorders. Detailed knowledge of these mechanisms will facilitate development of novel therapeutic approaches for the treatment of obesity and associated metabolic disorders.

Obesity associated disorders such as T2D, hypertension and CVD, commonly referred to as the “metabolic syndrome”, are prevalent diseases of industrialized societies. Deranged adipose tissue proliferation and differentiation contribute significantly to the development of these metabolic disorders. Comparatively little however is known, about how these processes influence the development of metabolic disorders. Using a multidisciplinary approach, I plan to elucidate molecular mechanisms underlying the altered adipocyte differentiation and maturation in different models of obesity associated metabolic disorders. Special emphasis will be given to the analysis of gene expression, postranslational modifications and lipid molecular species composition. To achieve this goal, I am establishing several novel methods to isolate pure primary preadipocytes including a new animal model that will allow me to monitor preadipocytes, in vivo and track their cellular fate in the context of a complete organism. These systems will allow, for the first time to study preadipocyte biology, in an in vivo setting. By monitoring preadipocyte differentiation in vivo, I will also be able to answer the key questions regarding the development of preadipocytes and examine signals that induce or inhibit their differentiation. Using transplantation techniques, I will elucidate the genetic and environmental contributions to the progression of obesity and its associated metabolic disorders. Furthermore, these studies will integrate a lipidomics approach to systematically analyze lipid molecular species composition in different models of metabolic disorders. My studies will provide new insights into the mechanisms and dynamics underlying adipocyte differentiation and maturation, and relate them to metabolic disorders. Detailed knowledge of these mechanisms will facilitate development of novel therapeutic approaches for the treatment of obesity and associated metabolic disorders.

SummaryCalcium-activated chloride channels (CaCCs) play key roles in a range of physiological processes such as the control of membrane excitability, photoreception and epithelial secretion. Although the importance of these channels has been recognized for more than 30 years their molecular identity remained obscure. The recent discovery of two protein families encoding for CaCCs, Anoctamins and Bestrophins, was a scientific breakthrough that has provided first insight into two novel ion channel architectures. Within this proposal we aim to determine the first high resolution structures of members of both families and study their functional behavior by an interdisciplinary approach combining biochemistry, X-ray crystallography and electrophysiology. The structural investigation of eukaryotic membrane proteins is extremely challenging and will require us to investigate large numbers of candidates to single out family members with superior biochemical properties. During the last year we have made large progress in this direction. By screening numerous eukaryotic Anoctamins and prokaryotic Bestrophins we have identified well-behaved proteins for both families, which were successfully scaled-up and purified. Additional family members will be identified within the course of the project. For these stable proteins we plan to grow crystals diffracting to high resolution and to proceed with structure determination. With first structural information in hand we will perform detailed functional studies using electrophysiology and complementary biophysical techniques to gain mechanistic insight into ion permeation and gating. As the pharmacology of both families is still in its infancy we will in later stages also engage in the identification and characterization of inhibitors and activators of Anoctamins and Bestrophins to open up a field that may ultimately lead to the discovery of novel therapeutic strategies targeting calcium-activated chloride channels.

Calcium-activated chloride channels (CaCCs) play key roles in a range of physiological processes such as the control of membrane excitability, photoreception and epithelial secretion. Although the importance of these channels has been recognized for more than 30 years their molecular identity remained obscure. The recent discovery of two protein families encoding for CaCCs, Anoctamins and Bestrophins, was a scientific breakthrough that has provided first insight into two novel ion channel architectures. Within this proposal we aim to determine the first high resolution structures of members of both families and study their functional behavior by an interdisciplinary approach combining biochemistry, X-ray crystallography and electrophysiology. The structural investigation of eukaryotic membrane proteins is extremely challenging and will require us to investigate large numbers of candidates to single out family members with superior biochemical properties. During the last year we have made large progress in this direction. By screening numerous eukaryotic Anoctamins and prokaryotic Bestrophins we have identified well-behaved proteins for both families, which were successfully scaled-up and purified. Additional family members will be identified within the course of the project. For these stable proteins we plan to grow crystals diffracting to high resolution and to proceed with structure determination. With first structural information in hand we will perform detailed functional studies using electrophysiology and complementary biophysical techniques to gain mechanistic insight into ion permeation and gating. As the pharmacology of both families is still in its infancy we will in later stages also engage in the identification and characterization of inhibitors and activators of Anoctamins and Bestrophins to open up a field that may ultimately lead to the discovery of novel therapeutic strategies targeting calcium-activated chloride channels.

SummaryHumans diverged from our closest living relatives, chimpanzees and other great apes, 6-10 million years ago. Since this divergence, our ancestors acquired genetic changes that enhanced cognition, altered metabolism, and endowed our species with an adaptive capacity to colonize the entire planet and reshape the biosphere. Through genome comparisons between modern humans, Neandertals, chimpanzees and other apes we have identified genetic changes that likely contribute to innovations in human metabolic and cognitive physiology. However, it has been difficult to assess the functional effects of these genetic changes due to the lack of cell culture systems that recapitulate great ape organ complexity. Human and chimpanzee pluripotent stem cells (PSCs) can self-organize into three-dimensional (3D) tissues that recapitulate the morphology, function, and genetic programs controlling organ development. Our vision is to use organoids to study the changes that set modern humans apart from our closest evolutionary relatives as well as all other organisms on the planet. In ANTHROPOID we will generate a great ape developmental cell atlas using cortex, liver, and small intestine organoids. We will use single-cell transcriptomics and chromatin accessibility to identify cell type-specific features of transcriptome divergence at cellular resolution. We will dissect enhancer evolution using single-cell genomic screens and ancestralize human cells to resurrect pre-human cellular phenotypes. ANTHROPOID utilizes quantitative and state-of-the-art methods to explore exciting high-risk questions at multiple branches of the modern human lineage. This project is a ground breaking starting point to replay evolution and tackle the ancient question of what makes us uniquely human?

Humans diverged from our closest living relatives, chimpanzees and other great apes, 6-10 million years ago. Since this divergence, our ancestors acquired genetic changes that enhanced cognition, altered metabolism, and endowed our species with an adaptive capacity to colonize the entire planet and reshape the biosphere. Through genome comparisons between modern humans, Neandertals, chimpanzees and other apes we have identified genetic changes that likely contribute to innovations in human metabolic and cognitive physiology. However, it has been difficult to assess the functional effects of these genetic changes due to the lack of cell culture systems that recapitulate great ape organ complexity. Human and chimpanzee pluripotent stem cells (PSCs) can self-organize into three-dimensional (3D) tissues that recapitulate the morphology, function, and genetic programs controlling organ development. Our vision is to use organoids to study the changes that set modern humans apart from our closest evolutionary relatives as well as all other organisms on the planet. In ANTHROPOID we will generate a great ape developmental cell atlas using cortex, liver, and small intestine organoids. We will use single-cell transcriptomics and chromatin accessibility to identify cell type-specific features of transcriptome divergence at cellular resolution. We will dissect enhancer evolution using single-cell genomic screens and ancestralize human cells to resurrect pre-human cellular phenotypes. ANTHROPOID utilizes quantitative and state-of-the-art methods to explore exciting high-risk questions at multiple branches of the modern human lineage. This project is a ground breaking starting point to replay evolution and tackle the ancient question of what makes us uniquely human?

Max ERC Funding

1 500 000 €

Duration

Start date: 2019-06-01, End date: 2024-05-31

Project acronymARTIVISM

ProjectArt and Activism : Creativity and Performance as Subversive Forms of Political Expression in Super-Diverse Cities

Researcher (PI)Monika Salzbrunn

Host Institution (HI)UNIVERSITE DE LAUSANNE

Call DetailsConsolidator Grant (CoG), SH5, ERC-2015-CoG

SummaryARTIVISM aims at exploring new artistic forms of political expression under difficult, precarious and/or oppressive conditions. It asks how social actors create belonging and multiple forms of resistance when they use art in activism or activism in art. What kind of alliances do these two forms of social practices generate in super-diverse places, in times of crisis and in precarious situations? Thus, ARTIVISM seeks to understand how social actors engage artistically in order to bring about social, economic and political change. Going beyond former research in urban and migration studies, and beyond the anthropology of art, ARTIVISM focuses on a broad range of artistic tools, styles and means of expression, namely festive events and parades, cartoons and comics and street art. By articulating performance studies, street anthropology and the sociology of celebration with migration and diversity studies, the project challenges former concepts, which took stable social groups for granted and reified them with ethnic lenses. The applied methodology considerably renews the field by bringing together event-, actor- and condition-centred approaches and a multi-sensory framework. Besides its multidisciplinary design, the ground-breaking nature of ARTIVISM lies in the application of the core concepts of performativity and liminality, as well as in an examination of the way to advance and refine these concepts and to create new analytical tools to respond to recent social phenomena. We have developed and tested innovative methods that respond to a postmodern type of fluid and temporary social action: audio-visual ethnography, urban event ethnography, street ethnography, field-crossing, and sensory ethnography (apprenticeship). Therefore, ARTIVISM develops new methods and theories in order to introduce a multi-faceted trans-disciplinary approach to the study of an emerging field of social transformations that is of challenging significance to the social sciences.

ARTIVISM aims at exploring new artistic forms of political expression under difficult, precarious and/or oppressive conditions. It asks how social actors create belonging and multiple forms of resistance when they use art in activism or activism in art. What kind of alliances do these two forms of social practices generate in super-diverse places, in times of crisis and in precarious situations? Thus, ARTIVISM seeks to understand how social actors engage artistically in order to bring about social, economic and political change. Going beyond former research in urban and migration studies, and beyond the anthropology of art, ARTIVISM focuses on a broad range of artistic tools, styles and means of expression, namely festive events and parades, cartoons and comics and street art. By articulating performance studies, street anthropology and the sociology of celebration with migration and diversity studies, the project challenges former concepts, which took stable social groups for granted and reified them with ethnic lenses. The applied methodology considerably renews the field by bringing together event-, actor- and condition-centred approaches and a multi-sensory framework. Besides its multidisciplinary design, the ground-breaking nature of ARTIVISM lies in the application of the core concepts of performativity and liminality, as well as in an examination of the way to advance and refine these concepts and to create new analytical tools to respond to recent social phenomena. We have developed and tested innovative methods that respond to a postmodern type of fluid and temporary social action: audio-visual ethnography, urban event ethnography, street ethnography, field-crossing, and sensory ethnography (apprenticeship). Therefore, ARTIVISM develops new methods and theories in order to introduce a multi-faceted trans-disciplinary approach to the study of an emerging field of social transformations that is of challenging significance to the social sciences.

Max ERC Funding

1 999 287 €

Duration

Start date: 2016-09-01, End date: 2022-02-28

Project acronymastromnesis

ProjectThe language of astrocytes: multilevel analysis to understand astrocyte communication and its role in memory-related brain operations and in cognitive behavior

Researcher (PI)Andrea Volterra

Host Institution (HI)UNIVERSITE DE LAUSANNE

Call DetailsAdvanced Grant (AdG), LS5, ERC-2013-ADG

SummaryIn the 90s, two landmark observations brought to a paradigm shift about the role of astrocytes in brain function: 1) astrocytes respond to signals coming from other cells with transient Ca2+ elevations; 2) Ca2+ transients in astrocytes trigger release of neuroactive and vasoactive agents. Since then, many modulatory astrocytic actions and mechanisms were described, forming a complex - partly contradictory - picture, in which the exact roles and modes of astrocyte action remain ill defined. Our project wants to bring light into the “language of astrocytes”, i.e. into how they communicate with neurons and, ultimately, address their role in brain computations and cognitive behavior. To this end we will perform 4 complementary levels of analysis using highly innovative methodologies in order to obtain unprecedented results. We will study: 1) the subcellular organization of astrocytes underlying local microdomain communications by use of correlative light-electron microscopy; 2) the way individual astrocytes integrate inputs and control synaptic ensembles using 3D two-photon imaging, genetically-encoded Ca2+ indicators, optogenetics and electrophysiology; 3) the contribution of astrocyte ensembles to behavior-relevant circuit operations using miniaturized microscopes capturing neuronal/astrocytic population dynamics in freely-moving mice during memory tests; 4) the contribution of astrocytic signalling mechanisms to cognitive behavior using a set of new mouse lines with conditional, astrocyte-specific genetic modification of signalling pathways. We expect that this combination of groundbreaking ideas, innovative technologies and multilevel analysis makes our project highly attractive to the neuroscience community at large, bridging aspects of molecular, cellular, systems and behavioral neuroscience, with the goal of leading from a provocative hypothesis to the conclusive demonstration of whether and how “the language of astrocytes” participates in memory and cognition.

In the 90s, two landmark observations brought to a paradigm shift about the role of astrocytes in brain function: 1) astrocytes respond to signals coming from other cells with transient Ca2+ elevations; 2) Ca2+ transients in astrocytes trigger release of neuroactive and vasoactive agents. Since then, many modulatory astrocytic actions and mechanisms were described, forming a complex - partly contradictory - picture, in which the exact roles and modes of astrocyte action remain ill defined. Our project wants to bring light into the “language of astrocytes”, i.e. into how they communicate with neurons and, ultimately, address their role in brain computations and cognitive behavior. To this end we will perform 4 complementary levels of analysis using highly innovative methodologies in order to obtain unprecedented results. We will study: 1) the subcellular organization of astrocytes underlying local microdomain communications by use of correlative light-electron microscopy; 2) the way individual astrocytes integrate inputs and control synaptic ensembles using 3D two-photon imaging, genetically-encoded Ca2+ indicators, optogenetics and electrophysiology; 3) the contribution of astrocyte ensembles to behavior-relevant circuit operations using miniaturized microscopes capturing neuronal/astrocytic population dynamics in freely-moving mice during memory tests; 4) the contribution of astrocytic signalling mechanisms to cognitive behavior using a set of new mouse lines with conditional, astrocyte-specific genetic modification of signalling pathways. We expect that this combination of groundbreaking ideas, innovative technologies and multilevel analysis makes our project highly attractive to the neuroscience community at large, bridging aspects of molecular, cellular, systems and behavioral neuroscience, with the goal of leading from a provocative hypothesis to the conclusive demonstration of whether and how “the language of astrocytes” participates in memory and cognition.

SummaryLearning and memory are the basis of our behaviour and mental well-being. Understanding the mechanisms of structural and cellular plasticity in defined neuronal circuits in vivo will be crucial to elucidate principles of circuit-specific memory formation and their relation to changes in neuronal ensemble dynamics.
Structural plasticity studies were technically limited to cortex, excluding deep brain areas like the amygdala, and mainly focussed on the input site (dendritic spines), whilst the plasticity of the axon initial segment (AIS), a neuron’s site of output generation, was so far not studied in vivo. Length and location of the AIS are plastic and strongly affects a neurons spike output. However, it remains unknown if AIS plasticity regulates neuronal activity upon learning in vivo.
We will combine viral expression of AIS live markers and genetically-encoded Ca2+-sensors with novel deep brain imaging techniques via gradient index (GRIN) lenses to investigate how AIS location and length are regulated upon associative learning in amygdala circuits in vivo. Two-photon time-lapse imaging of the AIS of amygdala neurons upon fear conditioning will help us to track learning-driven AIS location dynamics. Next, we will combine miniature microscope imaging of neuronal activity in freely moving animals with two-photon imaging to link AIS location, length and plasticity to the intrinsic activity as well as learning-related response plasticity of amygdala neurons during fear learning and extinction in vivo. Finally, we will test if AIS plasticity is a general cellular plasticity mechanisms in brain areas afferent to the amygdala, e.g. thalamus.
Using a combination of two-photon and miniature microscopy imaging to map structural dynamics of defined neural circuits in the amygdala and its thalamic input areas will provide fundamental insights into the cellular mechanisms underlying sensory processing upon learning and relate network level plasticity with the cellular level.

Learning and memory are the basis of our behaviour and mental well-being. Understanding the mechanisms of structural and cellular plasticity in defined neuronal circuits in vivo will be crucial to elucidate principles of circuit-specific memory formation and their relation to changes in neuronal ensemble dynamics.
Structural plasticity studies were technically limited to cortex, excluding deep brain areas like the amygdala, and mainly focussed on the input site (dendritic spines), whilst the plasticity of the axon initial segment (AIS), a neuron’s site of output generation, was so far not studied in vivo. Length and location of the AIS are plastic and strongly affects a neurons spike output. However, it remains unknown if AIS plasticity regulates neuronal activity upon learning in vivo.
We will combine viral expression of AIS live markers and genetically-encoded Ca2+-sensors with novel deep brain imaging techniques via gradient index (GRIN) lenses to investigate how AIS location and length are regulated upon associative learning in amygdala circuits in vivo. Two-photon time-lapse imaging of the AIS of amygdala neurons upon fear conditioning will help us to track learning-driven AIS location dynamics. Next, we will combine miniature microscope imaging of neuronal activity in freely moving animals with two-photon imaging to link AIS location, length and plasticity to the intrinsic activity as well as learning-related response plasticity of amygdala neurons during fear learning and extinction in vivo. Finally, we will test if AIS plasticity is a general cellular plasticity mechanisms in brain areas afferent to the amygdala, e.g. thalamus.
Using a combination of two-photon and miniature microscopy imaging to map structural dynamics of defined neural circuits in the amygdala and its thalamic input areas will provide fundamental insights into the cellular mechanisms underlying sensory processing upon learning and relate network level plasticity with the cellular level.

Max ERC Funding

1 475 475 €

Duration

Start date: 2018-12-01, End date: 2023-11-30

Project acronymBactInd

ProjectBacterial cooperation at the individual cell level

Researcher (PI)Rolf Kümmerli

Host Institution (HI)UNIVERSITAT ZURICH

Call DetailsConsolidator Grant (CoG), LS8, ERC-2015-CoG

SummaryAll levels of life entail cooperation and conflict. Genes cooperate to build up a functional genome, which can yet be undermined by selfish genetic elements. Humans and animals cooperate to build up societies, which can yet be subverted by cheats. There is a long-standing interest among biologists to comprehend the tug-of-war between cooperation and conflict. Recently, research on bacteria was successful in identifying key factors that can tip the balance in favour or against cooperation. Bacteria cooperate through the formation of protective biofilms, cell-to-cell communication, and the secretion of shareable public goods. However, the advantage of bacteria being fast replicating units, easily cultivatable in high numbers, is also their disadvantage: they are small and imperceptible, such that measures of cooperation typically rely on averaged responses across millions of cells. Thus, we still know very little about bacterial cooperation at the biological relevant scale: the individual cell level. Here, I present research using the secretion of public goods in the opportunistic human pathogen Pseudomonas aeruginosa, to tackle this issue. I will explore new dimensions of bacterial cooperation by asking whether bacteria engage in collective-decision making to find optimal group-level solutions; whether bacteria show division of labour to split up work efficiently; and whether bacteria can distinguish between trustworthy and cheating partners. The proposed research will make two significant contributions. First, it will reveal whether bacteria engage in complex forms of cooperation (collective decision-making, division of labour, partner recognition), which have traditionally been associated with higher organisms. Second, it will provide insights into the evolutionary stability of cooperation – key knowledge for designing therapies that interfere with virulence-inducing public goods in infections, and the design of stable public-good based remediation processes.

All levels of life entail cooperation and conflict. Genes cooperate to build up a functional genome, which can yet be undermined by selfish genetic elements. Humans and animals cooperate to build up societies, which can yet be subverted by cheats. There is a long-standing interest among biologists to comprehend the tug-of-war between cooperation and conflict. Recently, research on bacteria was successful in identifying key factors that can tip the balance in favour or against cooperation. Bacteria cooperate through the formation of protective biofilms, cell-to-cell communication, and the secretion of shareable public goods. However, the advantage of bacteria being fast replicating units, easily cultivatable in high numbers, is also their disadvantage: they are small and imperceptible, such that measures of cooperation typically rely on averaged responses across millions of cells. Thus, we still know very little about bacterial cooperation at the biological relevant scale: the individual cell level. Here, I present research using the secretion of public goods in the opportunistic human pathogen Pseudomonas aeruginosa, to tackle this issue. I will explore new dimensions of bacterial cooperation by asking whether bacteria engage in collective-decision making to find optimal group-level solutions; whether bacteria show division of labour to split up work efficiently; and whether bacteria can distinguish between trustworthy and cheating partners. The proposed research will make two significant contributions. First, it will reveal whether bacteria engage in complex forms of cooperation (collective decision-making, division of labour, partner recognition), which have traditionally been associated with higher organisms. Second, it will provide insights into the evolutionary stability of cooperation – key knowledge for designing therapies that interfere with virulence-inducing public goods in infections, and the design of stable public-good based remediation processes.

SummaryBrown adipocytes can dissipate energy in a process called adaptive thermogenesis. Whilst the classical brown adipose tissue (BAT) depots disappear during early life in humans, cold exposure can promote the appearance of brown-like adipocytes within the white adipose tissue (WAT), termed brite (brown-in-white). Increased BAT activity results in increased energy expenditure and has been correlated with leanness in humans. Hence, recruitment of brite adipocytes may constitute a promising therapeutic strategy to treat obesity and its associated metabolic diseases. Despite the beneficial metabolic properties of brown and brite adipocytes, little is known about the molecular mechanisms underlying their specification and activation in vivo. This proposal focuses on understanding the complex biology of thermogenic adipocyte biology by studying the epigenetic and transcriptional aspects of WAT britening and BAT recruitment in vivo to identify pathways of therapeutic relevance and to better define the brite precursor cells. Specific aims are to 1) investigate epigenetic and transcriptional states and heterogeneity in human and mouse adipose tissue; 2) develop a novel time-resolved method to correlate preceding chromatin states and cell fate decisions during adipose tissue remodelling; 3) identify and validate key (drugable) epigenetic and transcriptional regulators involved in brite adipocyte specification. Experimentally, I will use adipose tissue samples from human donors and mouse models, to asses at the single-cell level cellular heterogeneity, transcriptional and epigenetic states, to identify subpopulations, and to define the adaptive responses to cold or β-adrenergic stimulation. Using computational methods and in vitro and in vivo validation experiments, I will define epigenetic and transcriptional networks that control WAT britening, and develop a model of the molecular events underlying adipocyte tissue plasticity.

Brown adipocytes can dissipate energy in a process called adaptive thermogenesis. Whilst the classical brown adipose tissue (BAT) depots disappear during early life in humans, cold exposure can promote the appearance of brown-like adipocytes within the white adipose tissue (WAT), termed brite (brown-in-white). Increased BAT activity results in increased energy expenditure and has been correlated with leanness in humans. Hence, recruitment of brite adipocytes may constitute a promising therapeutic strategy to treat obesity and its associated metabolic diseases. Despite the beneficial metabolic properties of brown and brite adipocytes, little is known about the molecular mechanisms underlying their specification and activation in vivo. This proposal focuses on understanding the complex biology of thermogenic adipocyte biology by studying the epigenetic and transcriptional aspects of WAT britening and BAT recruitment in vivo to identify pathways of therapeutic relevance and to better define the brite precursor cells. Specific aims are to 1) investigate epigenetic and transcriptional states and heterogeneity in human and mouse adipose tissue; 2) develop a novel time-resolved method to correlate preceding chromatin states and cell fate decisions during adipose tissue remodelling; 3) identify and validate key (drugable) epigenetic and transcriptional regulators involved in brite adipocyte specification. Experimentally, I will use adipose tissue samples from human donors and mouse models, to asses at the single-cell level cellular heterogeneity, transcriptional and epigenetic states, to identify subpopulations, and to define the adaptive responses to cold or β-adrenergic stimulation. Using computational methods and in vitro and in vivo validation experiments, I will define epigenetic and transcriptional networks that control WAT britening, and develop a model of the molecular events underlying adipocyte tissue plasticity.

Max ERC Funding

1 552 620 €

Duration

Start date: 2019-03-01, End date: 2024-02-29

Project acronymCELLFUSION

ProjectMolecular dissection of the mechanisms of cell-cell fusion in the fission yeast

Researcher (PI)Sophie Geneviève Elisabeth Martin Benton

Host Institution (HI)UNIVERSITE DE LAUSANNE

Call DetailsConsolidator Grant (CoG), LS3, ERC-2015-CoG

SummaryCell fusion is critical for fertilization and development, for instance underlying muscle or bone formation. Cell fusion may also play important roles in regeneration and cancer. A conceptual understanding is emerging that cell fusion requires cell-cell communication, polarization of the cells towards each other, and assembly of a fusion machinery, in which an actin-based structure promotes membrane juxtaposition and fusogenic factors drive membrane fusion. However, in no single system have the molecular nature of all these parts been described, and thus the molecular basis of cell fusion remains poorly understood.
This proposal aims to depict the complete fusion process in a single organism, using the simple yeast model Schizosaccharomyces pombe, which has a long track record of discoveries in fundamental cellular processes. These haploid cells, which fuse to generate a diploid zygote, use highly conserved mechanisms of cell-cell communication (through pheromones and GPCR signaling), cell polarization (centred around the small GTPase Cdc42) and fusion. Indeed, we recently showed that these cells assemble an actin-based fusion structure, dubbed the actin fusion focus. Our five aims probe the molecular nature of, and the links between, signaling, polarization and the fusion machinery from initiation to termination of the process. These are:
1: To define the roles and feedback regulation of Cdc42 during cell fusion
2: To understand the molecular mechanisms of actin fusion focus formation
3: To identify the fusogen(s) promoting membrane fusion
4: To probe the GPCR signal for fusion initiation
5: To define the mechanism of fusion termination
By combining genetic, optogenetic, biochemical, live-imaging, synthetic and modeling approaches, this project will bring a molecular and conceptual understanding of cell fusion. This work will have far-ranging relevance for cell polarization, cytoskeletal organization, cell signalling and communication, and cell fate regulation.

Cell fusion is critical for fertilization and development, for instance underlying muscle or bone formation. Cell fusion may also play important roles in regeneration and cancer. A conceptual understanding is emerging that cell fusion requires cell-cell communication, polarization of the cells towards each other, and assembly of a fusion machinery, in which an actin-based structure promotes membrane juxtaposition and fusogenic factors drive membrane fusion. However, in no single system have the molecular nature of all these parts been described, and thus the molecular basis of cell fusion remains poorly understood.
This proposal aims to depict the complete fusion process in a single organism, using the simple yeast model Schizosaccharomyces pombe, which has a long track record of discoveries in fundamental cellular processes. These haploid cells, which fuse to generate a diploid zygote, use highly conserved mechanisms of cell-cell communication (through pheromones and GPCR signaling), cell polarization (centred around the small GTPase Cdc42) and fusion. Indeed, we recently showed that these cells assemble an actin-based fusion structure, dubbed the actin fusion focus. Our five aims probe the molecular nature of, and the links between, signaling, polarization and the fusion machinery from initiation to termination of the process. These are:
1: To define the roles and feedback regulation of Cdc42 during cell fusion
2: To understand the molecular mechanisms of actin fusion focus formation
3: To identify the fusogen(s) promoting membrane fusion
4: To probe the GPCR signal for fusion initiation
5: To define the mechanism of fusion termination
By combining genetic, optogenetic, biochemical, live-imaging, synthetic and modeling approaches, this project will bring a molecular and conceptual understanding of cell fusion. This work will have far-ranging relevance for cell polarization, cytoskeletal organization, cell signalling and communication, and cell fate regulation.

Max ERC Funding

1 999 956 €

Duration

Start date: 2016-10-01, End date: 2021-09-30

Project acronymCellularBiographies

ProjectGlobal views of cell type specification and differentiation

Researcher (PI)Alexander Schier

Host Institution (HI)UNIVERSITAT BASEL

Call DetailsAdvanced Grant (AdG), LS3, ERC-2018-ADG

SummaryEach cell in our body has a specific biography that is defined by its pedigree relationship with other cells (lineage) and by its history of gene expression (trajectory). A fundamental question in cellular and developmental biology has been how the lineage and trajectory of a cell lead to its specification and differentiation. Remarkable progress in genome editing and single-cell sequencing has generated the opportunity to understand this process at global scales and single-cell resolution. We have recently developed methods to reconstruct the cellular ancestry and transcriptional trajectories of cells during embryogenesis. The resulting lineage and trajectory trees can be analyzed to gain comprehensive views of how cellular diversity arises and how differentiation leads to physiologically specialized cell types. To generate such global views of cellular development, we will: 1. Define the cellular diversity and gene expression trajectories during zebrafish embryogenesis and organogenesis. Trajectory trees will be generated from scRNA-seq data and analyzed to reconstruct the gene expression pathways underlying fate specification. 2. Reveal the relationships between lineage and transcriptional trajectories during fate specification. Lineage trees will be generated by marking cells via genome editing and combined with trajectory trees to reveal the cellular paths towards fate specification. 3. Discover the gene expression cascades that remodel cells into physiologically functional types. Cell biological modules will be identified by comparing gene enrichment in differentiation trajectories and reveal the specialized and shared mechanisms of differentiation. These studies will help provide the first comprehensive and global view of the trajectories and lineages underlying vertebrate development. Our focus is on the zebrafish model system, but the data and concepts developed in this project will be applicable to other developmental and cellular systems.

Each cell in our body has a specific biography that is defined by its pedigree relationship with other cells (lineage) and by its history of gene expression (trajectory). A fundamental question in cellular and developmental biology has been how the lineage and trajectory of a cell lead to its specification and differentiation. Remarkable progress in genome editing and single-cell sequencing has generated the opportunity to understand this process at global scales and single-cell resolution. We have recently developed methods to reconstruct the cellular ancestry and transcriptional trajectories of cells during embryogenesis. The resulting lineage and trajectory trees can be analyzed to gain comprehensive views of how cellular diversity arises and how differentiation leads to physiologically specialized cell types. To generate such global views of cellular development, we will: 1. Define the cellular diversity and gene expression trajectories during zebrafish embryogenesis and organogenesis. Trajectory trees will be generated from scRNA-seq data and analyzed to reconstruct the gene expression pathways underlying fate specification. 2. Reveal the relationships between lineage and transcriptional trajectories during fate specification. Lineage trees will be generated by marking cells via genome editing and combined with trajectory trees to reveal the cellular paths towards fate specification. 3. Discover the gene expression cascades that remodel cells into physiologically functional types. Cell biological modules will be identified by comparing gene enrichment in differentiation trajectories and reveal the specialized and shared mechanisms of differentiation. These studies will help provide the first comprehensive and global view of the trajectories and lineages underlying vertebrate development. Our focus is on the zebrafish model system, but the data and concepts developed in this project will be applicable to other developmental and cellular systems.